A new report says one in three people in WA youth detention suffers from foetal alcohol spectrum disorder (FASD).

FASD results from an exposure to alcohol during pregnancy, and can cause brain damage in the unborn child, as well as delayed development and behavioural and learning problems.

Given these things become evident over time, FASD is often not diagnosed at birth.

A Telethon Kids Institute research project has looked at the prevalence of the neuro-developmental impairment among detainees at Banksia Hill Detention Centre, a youth custodial facility.

It found 30 to 40 per cent of the young people detained at Banksia Hill appeared to have FASD.

“Often these young people have trouble relating cause and effect,” lead researcher Carol Bower told the ABC.

“They can be easily influenced, their memory may not be good, they've often not done well at school.

“All of those things can really put you in situations where you can get in trouble with the law.”

Corrective Services Minister Joe Francis said it was disturbing, but not surprising.

“FASD is a major social and mental health issue that must be tackled at its source — before these kids are born — not after the damage is done,” Mr Francis said.

Labor's Corrective Services spokesman Paul Papalia agreed that a preventative approach is best.

“The one good thing you can say about it is it points the way to future policy development,” Mr Papalia said.

“We now have information that will allow us to tackle the problem.”

The Telethon Kids Institute Study is ongoing.

“We are developing educational resources for the staff at Banksia Hill to assist them in managing young people with neuro-developmental abnormalities,” Professor Bower said.

“I'm sure there will be lessons for us to learn from the families, from the young people, from the staff and from the community that will enrich and aid the recommendations that come from the study.”